1. Field of the Invention
This invention relates to a system for identifying a human individual, and in particular to an automatic palm print identification system adapted to convert the pattern of palm lines into a unique identifying code number for identifying the user of a credit card or the like.
2. Description of the Prior Art
In recent years, with the increasing use of computer terminals including point of sale, access control, and self-service banking devices, and with the increasing concern for the security and integrity of data stored in a computer file accessed from such remote terminals, there is a need to provide means for assuring that unauthorized individuals not be permitted to access that data or otherwise obtain services, credit, cash or information available to authorized users of such devices.
Thus, there exists a need for a personal identity verification system which will assure that the individual seeking access to the files or approval of a transaction is an individual entitled to the information or service. Accordingly, it has been suggested that finger print or palm print characteristics of the individual be digitized and recorded in the computer or on an I.D. or bank card. Then, the individual seeking access to data or a facility, or approval for a transaction would present his finger or palm for scanning and comparison to data on the card or in the computer file.
In one prior art device, the individual places his palm down upon a flat surface forming one edge of a prism, and the illuminated pattern of skin ridges and valleys is scanned by a photodetector to generate an output signal pattern which is digitized for comparison with data read from the I.D. card. A disadvantage of such an approach is that the palm contour is such that the hand must be pressed with great force against the planar surface in order to render the palm lines visible to the photodetector. Also, some individuals just cannot press hard enough to achieve total contact between the palm and a planar surface. This force causes a distortion of the lines and makes it difficult to receive repeatable results from successive analysis of the same palm. Of course, it is undesirable to reject as not verified an individual who is indeed the authorized individual. Thus, the inability to read the same palm with repeatable results becomes an embarrassment to the individual who is rejected improperly.
Also, if the master pattern for comparison is digitized and recorded on the magnetic stripe of an I.D. card, it is impractical to record on that card digital representations of the many lines which are on the palm or in a finger print. It would be highly desirable to be able to eliminate all except the darkest and most pronounced lines, so as to bring the total number of lines to be compared down to a low enough number that digital representations of them may be recorded in the limited space available in the magnetic stripe of the I.D. card.
Further, in scanning a palm to generate digital signals representative of the palm line spacing, the palm pattern generated is critically sensitive to the orientation of the hand with respect to the scan line, a slight inclination of the hand rendering the results between successive scannings significantly different. Consequently, it is desirable to provide a simple apparatus for scanning the palm lines which is not susceptible to slight variations in the orientation of the palm with respect to the scanning device.